Only pilfer once in InputSession.

This change modifies the behavior of InputSession to only pilfer
motion events once.

Fixes: 333596426
Test: atest InputSessionTest#testPilferOnce
Flag: ACONFIG com.android.systemui.dream_input_session_pilfer_once DISABLED
Change-Id: Ied60cbabcb4bed53f9ec77e580d722338f4de448
diff --git a/packages/SystemUI/aconfig/systemui.aconfig b/packages/SystemUI/aconfig/systemui.aconfig
index 15c31d5..94fd991 100644
--- a/packages/SystemUI/aconfig/systemui.aconfig
+++ b/packages/SystemUI/aconfig/systemui.aconfig
@@ -760,4 +760,14 @@
   metadata {
     purpose: PURPOSE_BUGFIX
   }
-}
\ No newline at end of file
+}
+
+flag {
+    name: "dream_input_session_pilfer_once"
+    namespace: "systemui"
+    description: "Pilfer at most once per input session"
+    bug: "324600132"
+    metadata {
+      purpose: PURPOSE_BUGFIX
+    }
+}